The invention pertains to the field of jet technology, primarily to the methods for producing a vacuum in the installations for processing a hydrocarbon feedstock and to pumping-ejection systems realizing these methods.
A method for producing a vacuum is known, which includes feeding a vapor ejecting medium into a gas ejector, evacuating a gaseous ejected medium by the vapor ejecting medium from an evacuated reservoir, mixing of the ejecting and ejected mediums and forming a mixture of the two, compressing the mixture due to its deceleration in a diffuser of the gas ejector, feeding a liquid ejecting medium into a nozzle of a liquid-gas ejector, evacuating the mixture of the vapor ejecting and gaseous ejected mediums from the gas ejector by the liquid-gas ejector, and forming a gas-liquid mixture in the liquid-gas ejector (see, DE, patent, 569423, class 27d,Jan., 1993).
An ejector-pump installation realizing the above method is also described in the mentioned patent. The installation includes a gas ejector and a liquid-gas ejector. The gas ejector is connected to a source of an ejected gaseous medium through its inlet for evacuated medium. An outlet of the gas ejector is connected to the evacuated medium inlet of the liquid-gas ejector.
The mentioned method and installation do not provide independent operation, this causes additional energy consumption.
The closest analogue of the method introduced in the invention is a method for producing a vacuum, which includes feeding a vapor ejecting medium into the gas ejector, evacuating a gaseous ejected medium from an evacuated reservoir by the vapor ejecting medium, mixing of the ejecting and ejected mediums and forming a mixture of the two, compressing the mixture due to its deceleration in a diffuser of the gas ejector, feeding a liquid ejecting medium into a liquid-gas ejector, evacuating the mixture of the vapor ejecting and gaseous ejected mediums from the gas ejector, forming a liquid-gas mixture in the liquid-gas ejector and simultaneous compressing the gaseous component of this mixture, feeding the liquid-gas mixture into a separator, separating the liquid-gas mixture into the liquid ejecting medium and compressed gas (see DE, patent 1092044, class 17 d May 5, 1960).
A pumping-ejection system with the closest complex of main features is also described in the above patent. It includes a gas ejector, a liquid-gas ejector, a separator, a pump and a pressure pipeline. The suction side of the pump is connected to the separator, the evacuated medium inlet of the gas ejector is connected to a source of an ejected gaseous medium, an outlet of the gas ejector is connected to the evacuated medium inlet of the liquid-gas ejector, the liquid inlet of the liquid-gas ejector is connected to the discharge side of the pump, an outlet of the liquid-gas ejector is connected to the separator through the pressure pipeline.
The above described method for producing a vacuum and pumping-ejection system realizing this method provide for independent operation of the circuit of feeding a liquid ejecting medium. However, the introduced engineering solutions require feeding of a vapor ejecting medium from an external source. This limits application range of the method and related system. Specialty of the pressure pipeline design is a point of vital importance because it can affect operation of the whole system. In addition, these engineering solutions do not provide optimum selection of ejecting mediums. The latter also hampers organization of fully independent operation of the system and often results in additional energy consumption.
The present invention is aimed at an increase in operational efficiency of the method for producing a vacuum and related pumping-ejection system.
The problem is solved as follows: a method for producing a vacuum, which includes feeding a vaporous ejecting medium into a gas ejector, evacuating a gaseous ejected medium from an evacuated reservoir by the vaporous ejecting medium, mixing of the ejecting and ejected mediums and forming a mixture of the two, compressing the mixture due to its slowdown in a diffuser of the gas ejector, feeding a liquid ejecting medium into a liquid-gas ejector through its liquid inlet, evacuating the mixture of the vaporous ejecting and gaseous ejected mediums from the gas ejector and forming a liquid-gas mixture with simultaneous compressing of the gaseous component of the liquid-gas mixture, feeding the liquid-gas mixture into a separator, separating the mixture in the separator into the liquid ejecting medium and compressed gas, is modified so that the vaporous ejecting medium of the gas ejector and the liquid ejecting medium of the liquid-gas ejector are reciprocally soluble in each other and the process steps of condensing the vaporous ejecting medium and dissolving condensate of the vaporous ejecting medium in the liquid ejecting medium after entry of the vaporous ejecting medium into the liquid-gas ejector, are additionally introduced thereto.
It is possible to arrange multi-step compression of the gaseous ejected medium in the gas ejector. In addition the method makes it is possible to organize drawing off a portion of the liquid ejecting medium from the separator, vaporizing this portion of the liquid medium and feeding it under pressure into the gas ejector as the vaporous ejecting medium.
As regards to an apparatus for embodiment of the introduced method, the mentioned technical problem is solved as follows: a pumping-ejection system, including
a gas ejector, whose evacuated medium inlet is connected to a source of an ejected gaseous medium and whose outlet is connected to the evacuated medium inlet of a liquid-gas ejector;
the liquid-gas ejector, whose liquid inlet is connected to the discharge side of a pump and whose outlet is connected to a separator through a pressure pipeline;
the separator;
the pump, whose suction side is connected to the separator;
the pressure pipeline,
is equipped with a vaporizing device for conversion of a portion of a liquid ejecting medium into the vaporous state, an inlet of the device is connected to the discharge side of the pump, an outlet of the device is connected to the ejecting medium inlet of the gas ejector, and length of the pressure pipeline represents from 0.2 to 400 times that of the pipeline diameter.
Research has shown that proper selection of ejecting mediums for gas and liquid-gas ejectors is the question of vital importance for operation of a two-phase pumping-ejection system. It was ascertained, that if substances or mixtures of substances chosen as a vaporous ejecting medium for the gas ejector and as a liquid ejecting medium of the liquid-gas ejector are well soluble in each other, such a mode of operation of the pumping ejection system is achievable, which provides an increased compression ratio of an ejected gaseous medium while load on the liquid-gas ejector and consequently level of energy consumption remain the same. This mode of operation is realized because the gas ejector provides an increased pressure at the evacuated medium inlet of the liquid gas ejector. Experiments have shown that liquid hydrocarbons (for example, gas oil) satisfy this condition best of all,. The use of hydrocarbons as the ejecting mediums allows transformation of a liquid medium into the vaporous state with considerably lower energy losses, if compared with water, for example. This, in turn, allows fully independent operation of the pumping-injection system because in this case a portion of the liquid ejecting medium of the liquid-gas ejector can be transformed into the vaporous state and used as the vaporous ejecting medium for the gas ejector. And what is more, operation of the liquid-gas ejector in the mode of quasi-isothermal compression can be provided. This is the most energetically advantageous mode of operation for a liquid-gas ejector being an element of the pumping-ejection system.
Another point of significant importance is design of the pressure pipeline. It was ascertained, that the pressure pipeline connecting the liquid-gas ejector with the separator, whose length represents from 0.2 to 400 times that of its diameter, provides most favourable conditions for full completion of the processes of dissolution of the vaporous ejecting medium and condensation of condensable components of the ejected gaseous medium in the liquid ejecting medium of the liquid-gas ejector prior to entry of the mediums into the separator. Thus, load on the separator is reduced and the separator performs only its original functionxe2x80x94the function of separation of a liquid-gas mixture into compressed gas and the liquid ejecting medium.